Question

The graph represents the distribution of the number of questions answered correctly on a 50-question math test.

A graph shows the horizontal axis numbered 24 to x. The vertical axis is unnumbered. The graph shows an upward trend from 24 to 36 then a downward trend from 36 to 48.
What is the standard deviation of the data?

4
8
12
24
Nico wanted to determine the number of students in his school who buy school lunch. He walked around the cafeteria one lunch period looking to see whether every fifth person in the cafeteria purchased lunch or brought their own.

Which method did he use to collect his data?

survey
simulation
experiment
observational study
The number of text messages that Reza sent each day so far in this billing cycle is shown on the dot plot.

A number line going from 1 to 13. 2 dots are above 2. 1 dot is above 3. 3 dots are above 6. 2 dots are above 7. 3 dots are above 8. 1 dot is above 11. 2 dots are above 12.
Which statement must be true according to the dot plot?

The data is symmetric and shows that he typically sent about 6 to 8 text messages per day.
The data is symmetric and shows that he sent 11 or 12 texts with the same frequency that he sent 1 or 2 texts.
The data is skewed and shows that he typically sent about 6 to 8 text messages per day.
The data is skewed and shows that he sent 11 or 12 texts with the same frequency that he sent 1 or 2 texts.
The residents of three towns were polled to find the percentage of residents who take a vacation in the summer or in the winter.

A 4-column table with 4 rows. The first column has no label with entries town 1, town 2, town 3, total. The second column is labeled summer with entries 567, 345, 143, 1,055. The third column is labeled winter with entries 87, 102, 158, 347. The fourth column is labeled total with entries 654, 447, 301, 1,402.

Which is the joint relative frequency of those in Town 2 who take a summer vacation? Round the answer to the nearest percent.

7%
10%
25%
75%

Answer 1

1) 4 — The distribution is centered at 36 with endpoints 24 and 48 (±12). If those are about ±3σ, σ = 12/3 = 4.

2) observational study — Nico simply observed people (no treatment, no asking/survey).

3) The data is symmetric and shows that he typically sent about 6 to 8 text messages per day. — The counts mirror around 7 and most dots are at 6–8.

4) 25% — joint relative frequency = 345/1402 ≈ 0.246 → 25%.